The typical clamp which is to be found in the home or industrial shop that is used to clamp workpieces of varying sizes is the well known "C" clamp having a pair of clamping surfaces one of which is linearly movable relative to the other. The linear movement of the moveable surface is accomplished by means of a hand operated turn screw. These clamps suffer a number of disadvantages in that they are awkward and slow in operation. Furthermore, frequently the clamp must be applied in a workspace where it is difficult for the workman to insert his hands in order to operate the turn screw with sufficient force to securely engage the workpiece.
To minimize these disadvantages, a number of clamping devices have been proposed in which the clamping force applied to provide secure clamping is lever actuated. Examples of such clamps are found, for example, in U.S. Pat. Nos. 2,905,038 and 3,836,136. In these devices, one clamping surface is slidably mounted on a toothed bar. The other clamping surface is connected to a lever in a manner that allows it to move linearly with movement of the lever.
In use, a workpiece is placed between the clamping surfaces and against the lever actuated surface. The slidable member is moved into position against the workpiece. Then the lever is moved to force its associated clamping surface against the workpiece to provide secure engagement.
These devices, while they overcome some of the disadvantages associated with the typical "C" clamp, remain somewhat awkward to operate. Clearly, therefore, it would be desirable to have available an adjustable clamp capable of being operated more efficiently than those already known to the art.